Drawing glass sheets



H. G. SLJNGLUFF.

DRAWING GLASS SHEETS.

APPLICATION FILED JULY 11, 1915.

1,339,229. Patented y 4,1920.

2 SHEETSSHEET I.

INVENTOR H. G. SLINGLUFF.

DRAWING GLASS SHEETS.

APPLICATION FILED JULY n. 1918.

Patented May 4, 1920.

2 SHEETS-SHEET 2.

mvsm'on UNITED STATES PATENT OFFICE.

HARRY G. SLINGLUFF, 0F MOUNT VERNON, OHIO, ASSIGNOR TO PITTSBURGH PLATE GLASS COMPANY, A CORPORATION OF IENNSYLVANIA,

DRAWING GLASS SHEETS.

Specification of Letters Patent.

Patented May 4, 1920.

Application filed July 11, 1918. Serial No. 244,365.

To all whom it may concern:

Be it known that I, HARRY G. SLINGLUFF, a citizen of the United States, residing at Mount Vernon, in the county of Knox and State of Ohio, have invented certain new and useful Improvements in Drawing Glass Sheets, of which the following is a specification.

The invention relates to the art of drawing glass sheets continuously, and has for its primary objects, the provision of improvements whereby the temperature of the glass in that part of a drawing tank from which sheet is pulled may be controlled, thus giving control of the thickness of the sheet, the speed of drawing and the condition of the glass, and the provision of improved means for maintaining the width of the sheet being drawn. One form of apparatus which may be employed is disclosed in the accompanying drawings, wherein:

Figure 1 is a transverse vertical section through the apparatus, Fig. 2 is a vertical section through the a paratus at right angles to the section of *ig. 1, Fig. 3 is an enlarged side elevation of the chilling bar employed, and Figs. 1 and 5 are sections on the lines IVIV and VV of Fig. 3.

Referring first to the general arrangement as shown in Figs. 1 and 2, the reference numeral 1 indicates a drawing tank'or extension communicating at its left hand end with the melting furnace 2; 8 and 4 are sections of the furnace roof or top} 5 and (3 are other roof sections provided with the depending portions 7 and 8, which for lack of a better designation may be termed curtain blocks; 9, 9 are supporting trucks or carriers working between the pairs of channels 10 and 10 (Fig. 2); 11 is a chilling block lying beneath the surface of the glass; 12 is a glass sheet which is being drawn; and 18 is a bait by means of which thestarting of the drawing operation is accomplished, a preferred means for continuing the drawing operation after it is started being illus trated in my pending application, Serial No. 225,190, filed March 28, 1918. Such application also discloses the chilling bar shown in detail in Figs. 3, 1 and 5 of the present application. i The movable roof or top sections 5 and 6 are preferably provided with the transverse reinforcing bars 14, such bars being provided at their ends with heads and nuts,

as indicated in Fig. 2, and serving to secure in position the angle irons 15 by means of which the roof sections are supported. The truck members 9are each provided with depending hangers secured at their lower ends through the angle irons 15, and such truck members are also provided with the pairs of wheels 17 working upon the flanges of the channel bars 10. Mounted upon the channel bars 10 are the sprocket wheels 17 over which extend the chains 18 secured at 19 to the truck members, so that a movement of the chains causes a movement of the truck members and the roof members supported thereby. In order that corresponding truck members on'both sides of the furnace may be operated together the shafts 20 are provided (Fig. 2) extending from a sprocket 17 on one side of the furnace to a corresponding sprocket on the other side. The outer end of each of these shafts 20 is provided with a sprocket wheel 21 (Fig. 2) around which extends a depending endless chain 22 so that the shafts 20 may be con veniently rotated from beneath to cause the movement of the truck members either toward the sheet of glass being, drawn or away from it.

The furnace construction as illustrated in Fig. 1 provides a pair of chambers 23 and 24 lying to the rear of the curtain blocks 7 and 8, heat being supplied to the chamber 23 from the melting tank 2 and to the chamber 24 by means of the end burners 25 and side burners 26. By this means glass in the drawing tank 1 is maintained at a relatively high temperature, while that portion of the surface of the body of glass lying between the curtain blocks 7 and 8 is shielded from the heat in the chambers 23 and 24 and permitted to cool below the temperature of the main body of glass in the tank by reason of the heat radiated from the exposed area and by means of the cooling action of the atmosphere. The temperature of the glass directly beneath the line of generation of the sheet is also reduced by reason of the bar 11 which exercises a chilling effect upon the body of glass lying immediately above it. The portions of the glass, therefore, from which the drawing occurs are relatively cool and viscous, while the surrounding body of glass is at a relatively high temperature, a condition which has been found conducive to the successful production of a glass sheet and to the carrying out of a continuous operation. During the drawing of the sheet, however, the condition of the lass in the area between the curtain blocks and 8 may be changed considerably incident to changes of temperature in the chambers 23 and 24, and incident to changes in the amount of heat radiated from the surface of the glass and conducted away by the atmosphere, so that with a continuous rate of drawing speed the thickness offlie sheet will vary, such thickness increasing as the temperature of the lass in the drawing opening decreases andecreasing in thickness as such tern erature increases. For instance, as the rawing prograsses it has been found that the usual tendency is for'thelfody of glass in the drawing opening'to g'ra nazll become cooler causi c an increase in thickness of the sheet. l d erder tocompemsate for these varying conditions, the roof sections 5 and 6 have been made adjustable as illustrated and heretofore desm-iibed, and the temperature of the glass in the drawing opening may be modified do!" the drawing operation by adjusting the position of the dependin r curtain blocks with to the sheet. s these blocks or members-are made to appreac'l-i each other the area of glass e sed to radiation and cooling is decreased t us tendin to increase the tere of the glass. imilarl'y, if the glass in the drawing area becomes too hot and fluid, a movement of the curtain blocks away from the sheet increases the area of the glass e and consequently secures a mduotion in the temperature of the lass. The curtain blocks, therefore, ma gradually moved toward or from eac otherl the drawing operation depending rnpen dhe rm uiremimts, thus compensatingtor changes of Itempemtnne in the chambeus23 and Q! and dior ch es incident to other causes such as :a variamon in the rate of imm "the exposed d'wwing area.

In order to dose (the spaces 27 at the ends of the cuntaisn block members the side'memhers -28 are provided as indicated in F [1, such side members having their lower ages :md fitting inside the wall portions 129 as indicated in Fig. 2. These side wall members 28 also serve to add strength and are mpport to the curtain blocks themwas.

dive dlilli bar 11 iisprefnrably made as 'mdielbd in i/gs. '3, 4, and 5, such chilling bar be' provided at its ends with the drawing menillllalems 80. As 8?. fourth n c ew up "oafiom hsmete one neientd do, numbers mm to maintain 60 th: pom-cilia 31 offthesheet in r931; l-u u 7"1;

'ismmplished by tlhe'nseufiihe pne- 115.82 l'vng relatively close to the ues of the glass and providing bemlthentheglwves33shewninfig. 5.

The glass in these grooves 33 is partially segregated from the main body of glass and chilled by the surrounding body of clay so that a small volume of relatively cool viscous glass is provided at each ed e of the sheet. The relatively small vo umes or pockets of glass in the grooves adhere .to the clay between the projections 32 and to the edges 31 forming a viscous bond or anchor from which such edges are stretched out or drawn. These edges bei cooler and stiffer than the main body of sheet maintain their position despite the natural tendency of the sheet *to narrow down as rtihe drawing progresses.

As indicated by the dotted lines 34 the grooves extend to the ends of the blocks and increase in depth thus proivilh'ng passage ways from which new glass is supplied to take the place of the glass drawn out by the edges 31. This supply of fresh and relatively hotter glass from the ends of the blocks permits of the continuous and uniform drawing action. If it were not for this supply of glass, the glass at the inner ends of the grooves would radually become more viscous causing !the e s 31 to thicken up and destroying the uniformity of the edges and eventually interfering with the further production of the sheet.

The provision of the 35 extending along the upper portion of :the bar 11 (Fig. 4) tends to prevent the lateral movement of the line of generabionof'the sheet, and tends to keep the sheet flat and in .alinement with the upper edge of the bar. This is due to the fact that the tendency of the sheet is to pull from the line of greatest resistance, and theglass immediately above the peak of the ridge is cooler and stifier than that von either side of such peak. The bar can be placed with its upper edge relatively close to the surface of the glass without causing any marring of the surface of the sheet and this proximity of the ole. to the line of generation has a chilling e ect upon the glass from which the drawing occurs, permitting of a maximum speed of draw. he bar 11 may be held in position in the tank by means of the blocks 36, fitting into the side walls of the furnace (Fig. 2) or by any other suitable means. Other advantages incident to the use of the chilling bar and to the use of the drawing blocks or members at the ends of such bar will be readily apparent to those skilled in the art.

The members 30, although integral with the bar 11, are refenred to heretofore separately to indicate that it is not essential that these portions or parts for maintaining the position of the e@es of the sheet be :made integral with the bar, which fact is clear from a consideration of my pending appllication heretofore referred. Such ap- .plication shows drawing blocks, which in most instances, are separate from the chilling bar, and the making of the chilling bar and the drawing blocks integral as is here done merely involves a matter of convenience.

that I claim is:

1. In glass drawing apparatus, a tank adapted to contain a body of molten glass, means at each side thereof for maintaining the position of the edge of a sheet of glass being drawn comprising a body of refractory material lying beneath the surface of the glass and provided on its upper side with a groove whose inner portion constitutes the locus of generation of the edge of the sheet, and a chilling bar extending between said means.

2. In glass drawing apparatus, a tank adapted to contain a body of molten glass, and means at each side thereof for maintaining the position of the edge of a sheet of glass being drawn comprising a body of refractory material lying beneath the surface o t the glass and having its upper surface tapering upwardly and inwardly and provided with a groove whose inner portion constitutes the locus of generation of the edge of the sheet.

In glass drawing apparatus, a tank adapted to contain a body of molten glass, and means at each side thereof for maintaining the position of the edge of a sheet of glass being drawn comprising a body of refractory material lying beneath the surface of the glass and provided on its upper side with a groove whose inner portion constitutes the locus of generation of the edge of the sheet, said groove extending to the outer end of the said body and increasing in cross section from its inner to its outer end.

4. In glass drawing apparatus, a tank adapted to contain a body of molten glass, and means at each side thereof for maintaining the position of the edge of a sheet of glass being drawn comprising a body of refractory material lying beneath the surface of the glass and having its upper surface tapering upwardly and inwardly and provided with a groove whose inner portion constitutes the locus of generation of the edge of the sheet, said groove extending to the outer end of said body and constituting a passageway for the supply of glass to the inner portion of the groove.

The combination with a glass tank having a top provided with an opening exposing a portion of the surface of the glass in the tank. to the cooling action of the atmos phere, of means for drawing a glass sheet from the opening, a chilling bar of refractory material adapted to lie in the body of molten glass beneath the line of draw of the sheet to be produced, and means at each end of the bar for maintaining the position of the edge of the sheet, such means including upwardly projecting means on the end of the bar with a groove therebetween to permit of a supply of glass from the outer end of the bar.

6. The combination with a glass tank having a top provided with an opening exposing a portion of the surface of the glass in the tank to the cooling action of the atmosphere, of means for drawing a glass sheet from the opening, a chilling bar of refractory material having its upper surface tapering to form a ridge and adapted to lie in the body of molten glass beneath the line of draw of the sheet to be produced, and means at each end of the bar for maintaining the position of the edge of the sheet, such means including upwardly projecting means on the end of the bar with a groove therebetween to permit of a supply of glass from the outer end of the bar.

7. The combination with a glass tank having a top provided with an opening exposing a portion of the surface of the glass in the tank to the cooling action of the atmosphere, of means for drawing a glass sheet from the opening, a chilling bar of refractory material adapted to lie in the body of molten glass beneath the line of draw of the sheet to be produced and having its upper surface tapering to a peak, and an anchoring means at each end of the bar for maintaining the position of the edges of the sheet. I

*8. The combination with a glass tank having a top provided with an opening exposing a portion of the surface of the glass in the tank to the cooling action of the atmosphere, of means for drawing a glass sheet from the opening and a chilling bar of refractory material adapted to lie in the body of molten glass beneath the line of draw of the sheet to be produced and having its upper surface tapering to a peak.

9. The combination with a glass tank hav ing a top provided with an opening exposing a portion of the surface of the glass in the tank to the cooling action of the atmosphere, of means for drawing a glass sheet from the opening, a chilling bar of refractory material adapted to lie in the body of molten glass beneath the line of the draw of the sheet to be produced, and means at each end of the bar for maintaining the position of the edge of the sheet, such means comprising a groove in the upper surface of the bar.

In testimony whereof, I have hereunto subscribed my name this 17th day of June, 1918.

HARRY Gr. SLINGLUFF.

Witnesses:

BANNER M. ALLEN, J. W. JoNEs. 

